Hi,
The description used for the example case was "GUARDADO5", and I´m sure I can use the flow if i don´t use the dynamic content from my sharepoint.
I find a way to sort this problem out. My SharePoint is linked to a Power App so in that Power app I just created an HTML text control, paste my HTML text and save that HTML control into a SharePoint List field. Then, in the flow I created I just put the variable as that SharePoint list field and it worked.
Either way, thanks for your comments.